Why are liberals calling for this Supreme Court justice to step down?

Liberal court-watchers are getting nervous again about Ruth Bader Ginsburg. This week, liberal scholar Erwin Chemerinsky wrote in an op/ed that Supreme Court Justice Ruth Bader Ginsburg should retire this summer. Here's a closer look at what he and others have argued. It's the only way to guarantee a liberal successor. After November's elections, it's possible the Senate will be controlled by Republicans. (Getty Images) The argument: The Senate will likely be controlled by Republicans after the fall elections. They …